The present invention relates to an automobile airbag door that is opened when torn by pressing force of an airbag being deployed and inflated.
Conventionally, an automobile is equipped with a front passenger seat airbag apparatus as a means for protecting the occupant on the front passenger seat (for example, refer to Japanese National Phase Laid-Open Patent Publication No. 2005-537164). In the front passenger seat airbag apparatus, a part of the instrument panel arranged in front of the front passenger seat of the automobile forms an airbag door. The airbag door includes a base member, which serves as a core member, and a cover member bonded to the surface of the base member. The cover member includes a cushion layer bonded to the surface of the base member and a covering bonded to the surface of the cushion layer. The covering includes a ground fabric layer and a covering layer bonded to the surface of the ground fabric layer.
Some airbag doors have a three-dimensionally knitted cushion layer, which is, for example, configured by double-raschel knitted fabric, to give elasticity to the airbag door, thereby improving the tactile sensation.
The airbag door has a tear line (a tearable line), which is formed by a plurality of short cleavage grooves or a single elongated cleavage groove and functions as the starting point of tearing leading to an opening action. The tear line allows the airbag door to be smoothly opened and the airbag to be smoothly deployed and inflated. To be inconspicuous from the surface side of the airbag door, the tear line is formed on the back side of the airbag door. For example, a tear line is formed in each of the base member and the cushion layer. In addition to the tear lines formed in the base member and the cushion layer, some airbag doors are also provided with a tear line formed in the back side of the covering.
When an impact is applied from the front to an automobile equipped with the above described front passenger seat airbag apparatus, for example, due to a frontal collision, the inflator supplies inflation gas to the airbag to deploy and inflate the airbag. The airbag in turn presses the airbag door, thereby tearing the base member and the cover member along the tear lines to open the airbag door. The airbag passes through the opening, which is formed by opening the airbag door, to be deployed and inflated between the instrument panel and the occupant seated on the front passenger seat, thereby reducing the impact applied to the occupant from the front.
In conventional airbag doors, a tear line is formed at least in the cushion layer in the cover member to allow the cover member to be torn along the tear line in the base member. This requires a step for forming a tear line at least in the cushion layer and a step for bonding the cushion layer to the surface of the base member such that the tear line in the base member and the tear line in the cushion member are aligned with each other. As a result, problems such as an increased number of manufacturing steps are brought about.